I prefer the Wolverine, but that's a playstyle thing. Technically the worst gun, but still good enough to damage most stuff you'll face, and the RoF is awesome, plus the turret lets you take advantage of more positions than the non-turreted peers.

I really don't think you can go too wrong with any one of them. The SU-85 is very powerful with the 107mm, the StuG is a stealthy assassin, and the Wolverine hits hard with a turret (that's a big plus). I've had relatively less success with the Russian TDs than the American or German TDs, and that trend continued in tier 5, but that's just me. That said, driving a KV or T1 Heavy, the only thing I really feared in tier 3-5 matches was the SU-85, because of the powerful alpha strike.

after using all three i have to say Su85. with the 107 its great...you can one-shot some tanks. the wolverine is fun but feels like a peashooter, and the stug is a great sniper but doenst hit that hard so can be really vulnerable closeup.

I found the Wolverine to be sex. It's gun tore apart everything very quickly, and the turret made tracking targets much easier. The stug was zippy, and had a decent gun, but lacked armor. Never tried the Su-85, but i've found them to be pretty squishy on the battlefield.

I have to say Stug. It's very agile, it hides well, it has an effective gun. Followed by M10 with its 76mm autocannon and turret-related options. SU-85 trails the others because, while its gun is exceedingly powerful, it's not accurate and it's very slow. It doesn't excel at making 400+ meter shots, and as your hit ratio goes progressively up at shorter ranges you are more likely to be spotted and ganked while reloading. I loved SU-85 to pieces in beta because of that huge gun, but now that I've gotten better at concealment and finding good long-range shot opportunities, I find it to be lacking.

I played all 3 and I found the SU-85(in beta) powerful start game but weak end game finish. It can do well with other tanks around to spot, but once your one of the few left on the field. You pretty much a sitting duck due to the horrible view range. It does have a powerful gun but it's not as accurate because of the slow reload it's easy to miss and get flanked when you have little support in the end game. Quick start hard to finish.

While the Wolverine I tend to get higher Win Loss and Kill Death ratios, because it is more versatile, you can actually spot enemies coming at you (thus have a chance to kill them!) and the decent penetration and fast ROF makes it good both against faster lower tier tanks as well as some higher more armored tanks.

The Stug has a fast ROF and accuracy for it's derp gun. Making it the best hit and reposition vehicle. It's not the best but it's not the worst either! I first used the 75 and tried to pick people off, but it has poor view range like the SU-85 (but not as bad as the SU!) so it became useless late match. So I switched and tried the 105, then I got 9 kills that game (was the last 2 tanks). Haven't looked back. I like the faster firing derp gun cause when you miss, and you will with a derp, or when you are out numbered that that little bit of extra reload time makes a world of difference!

The SU-85 is wonderful but the low accuracy can lead to some issues. Fortunately for it, that is really it's only weakness - it even has halfway decent armor for this tier, sharing the hull of the T-34.

I will defend the wolverine; aside from the turret, it's nice having the choice of the 76 AT or 105 howitzer. With the 76, there's a lot of potential for long range harassment if you can keep yourself out of the enemy's line of fire. I remember it being quite fun, myself. I'll probably buy one again sometime.

Stug is alright, but I felt it was weak for the tier. It's snipey, but if shot at it's almost certainly toast on the first shot - which will pen it 90% of the time because the stug has shit for armor.

I used to play medium and heavy tanks, have to say neither su85 nor US TDs could survive after they are spotted, because their armor is weak and HP is low, and after they shoot I shoot back very quickly and kill them before they hide again.
yes the turret of slugger has strong front armor, but everyone shoot at body not the turret. so,

if all TDs could not survive after enemy tanks fire back, powerful gun makes sense, and su85 can hide in bush well, to hide a US TD is as hard as to hide an elephant